This invention relates generally to ambulatory medical systems that include a medical device and a control device that communicate via telemetry and that initiate message reception during predefined listening periods. Preferred embodiments relate to implantable infusion pumps and external devices for communicating therewith.
Various ambulatory medical devices have been proposed and a number of such devices are commercially available. These devices include, for example, implantable infusion pumps, externally carried infusion pumps, implantable pacemakers, implantable defibrillators, implantable neural stimulators, implantable physiological sensors, externally carried physiologic sensors, and the like.
As appropriate operation of ambulatory medical devices may be critical to those patients being treated using those devices, and as telemetry communications between ambulatory medical devices and controllers can greatly enhance the convenience of using such devices, or even be an enabling necessity to the use of such devices (e.g. implantable devices with sophisticated functionality), the operation of such medical devices can benefit significantly by use of telemetry systems and protocols that have features/elements that lead to optimization of various attributes. Such attributes may include (1) flexibility in communicating the wide variety signals that may be useful to controlling and retrieving information from a sophisticated medical device, (2) robustness in distinguishing actual signals from noise, (3) robustness in distinguishing valid signals from corrupt signals, (4) robustness in ascertaining when appropriate communication has occurred and when additional communication must be attempted, (5) a reasonable efficiency in communication time, and/or (6) a reasonable efficiency in electrical power consumption associated with conveying information over the telemetry system.
Implantable medical devices typically operate by battery power. The batteries may or may not be rechargeable. Higher consumption of power from an implantable medical device containing non-rechargeable batteries leads to a shortening of the usable life of the device and an associated increased frequency of surgery, potential pain, recovery, and inconvenience. Higher consumption of power from an implantable medical device containing rechargeable batteries leads to more frequent charging periods for the batteries and associated inconvenience and may lead to an overall shortening of the usable life of the device. As such, whether or not an implantable medical device contains rechargeable batteries or non-rechargeable batteries, it is desirable to lower the power consumption of the device. As telemetry reception and transmission are highly energy consumptive, it is desirable to minimize the operation time of telemetry reception and transmission modules.
A telemetry reception module of a first device needs to (1) be powered to listen for potential incoming messages from a second device, (2) stay powered during the entire receipt of the message, and (3) potentially be powered one or more repeated times to receive a duplicate message when the second device is expecting a response to its original message and does not receive one. A telemetry transmission module of a first device needs to (1) be powered so it can transmit a desired message to a second device, and (2) potentially be powered one or more times to retransmit a duplicate message when the first device fails to receive confirmation that original message was received by the second device.
A need exists in the field for improved telemetry features/elements that tend to minimize one or both of power on time for telemetry reception modules and/or telemetry transmission modules to reduce power drain on batteries used in powering ambulatory medical devices and communicators. A need exists in the field to ensure that device users are not inconvenienced with long delay times that may be associated with inputting information into the communication device, transmitting information via telemetry to the medical device, and waiting for confirmation that the transmitted information was appropriately received and is was or will be appropriately acted upon.
It is a first object of certain aspects of the invention to reduce power consumption in an ambulatory medical system associated with receiving messages via telemetry.
It is a second object of certain aspects of the invention to reduce power consumption in an ambulatory medical system associated with transmitting messages via telemetry.
It is a third object of certain aspects of the invention to shift power consumption burdens associated with telemetry activities away from an implantable medical device to an external communication device.
It is a fourth object of certain aspects of the invention to achieve enhanced synchronization between timers in the medical device and in the communication device than is inherently achieved based on frequency oscillation tolerance differences allowed in the principle oscillators used in the two devices.
Other objects and advantages of various aspects of the invention will be apparent to those of skill in the art upon review of the teachings herein. The various aspects of the invention set forth below as well as other aspects of the invention not specifically set forth below but ascertained from the teachings found herein, may address the above noted objects or other objects ascertained from the teachings herein individually or in various combinations. As such, it is intended that each aspect of the invention address at least one of the above noted objects or address some other object that will be apparent to one of skill in the art from a review of the teachings herein. It is not intended that all, or even a portion of these objects, necessarily be addressed by any single aspect of the invention even though that may be the case with regard to some aspects.
It is a first aspect of the invention to provide a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the CD telemetry system listens during preselected outbound listening periods for at least a selected type of message from the MD telemetry system.
In a specific variation of the first aspect of the invention, the medical device is capable of initiating communication with the communication during outbound listening periods, and the communication device additionally includes (a) a CD clock system; (b) CD monitoring system that monitors a CD time, based on the CD clock system, that corresponds to a selected portion of a message received by the CD telemetry system from the MD telemetry system; and (c) a CD control system for effectively comparing the CD time to an anticipated outbound transmission start time by the MD telemetry system for that selected portion of the message to adaptively adjust a subsequent outbound listening period based, at least in part, on the comparison of the CD time to the anticipated outbound transmission start time.
In another variation of the first aspect of the invention, the MD telemetry system activates a window for receiving messages from the CD telemetry system during prescribed inbound listening periods and wherein successive prescribed inbound listening periods are separated by a smaller interval than an interval that separates successive outbound listening periods.
A second aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the CD telemetry system does not send out a message as the message is generated but instead delays the sending out of a message until a next prescribed inbound transmission start time occurs.
A third aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the MD telemetry system listens for any messages coming from the CD telemetry system beginning at prescribed inbound listening start times for prescribed inbound listening periods.
In a specific variation of the third aspect of the invention, the communication device attempts to anticipate the prescribed inbound listening periods and sets inbound transmission start times to correspond to the anticipated prescribed inbound listening periods.
In another specific variation of the third aspect of the invention, the prescribed inbound listening start times and prescribed inbound listening periods are determined and activated automatically without microprocessor intervention.
A fourth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the MD telemetry system and the CD telemetry send and receive messages using digital modulation and demodulation.
In a specific variation of the eleventh aspect of the invention the digital modulation and demodulation uses spread spectrum technology.
In another specific variation of the eleventh aspect of the invention, the MD telemetry system includes (1) a digital modulator, (2) a receiving amplifier, (3) a digital receiver, (4) a mixer, and (5) a low pass filter wherein at least two of (1)-(5) are combined into a single integrated circuit or where all of (1)-(5) are combined into no more than two integrated circuits.
A fifth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least one of the communication device or the medical device sets a preamble length, for at least some messages, as a function of at least the difference between a present time and a time of a previous communication.
In a specific variation of the fifth aspect of the invention, the estimated listening time is based, at least in part, on a time difference between the present time and a time of a previously received message. In a further variation, the communication device derives the estimate. In still a further variation a transmission time is based, at least in part, on a predefined desired transmission time as modified by an estimated amount of drift that may have occurred between a time base used by the medical device and a time base used by the communication device
A sixth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least one of the communication device or the medical device determines an estimated listening time for the other of the communication device or the medical device and sets a transmission start time as a function of the estimated listening time.
A seventh aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the medical device or the communication device comprises an oscillator circuit that produces a pulse stream that oscillates at an initial frequency that is greater than a desired frequency and wherein signals from the oscillator circuit are passed through circuitry that removes selected pulses from an input pulse stream such that a modified oscillator signal is produced having a modified pulse stream that oscillates with an average frequency closer to a desired frequency than the initial frequency.
In a specific variation of the seventh aspect of the invention, the circuitry comprises a counter that repetitively counts to a first predefined value and then removes a pulse from the initial pulse stream to produce the modified pulse stream. In a further variation, a timing signal is generated from the modified pulse stream by utilization of a counter that counts to a second predefined value and then outputs a pulse. In a further variation, the first predefined value is defined by software. In still a further variation, the first predefined value is subject to modification during a normal course of operation of the medical system. In still a further variation, the modification of the first predefined value causes the modified pulse stream to oscillate at a frequency closer to the desired frequency than it otherwise would if it remained unchanged. In still a further variation the modification of the first predefined value is at least in part based on a temperature of the oscillator circuit.
An eighth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least one of the medical device or the communication device periodically adjusts a concept of time to match at least in part a concept of time in the other of the communication device or the medical device.
In a specific variation of the eighth aspect of the invention, the concepts of time of the medical device and the communication device are used by each for controlling, at least in part, telemetry operations of the medical device and communication device, respectively.
In another specific variation of the eighth aspect of the invention, a first of the communication device or the medical device adjusts a first concept of time to match that of the second of the communication device or medical device, while the second of the medical device or the communication device matches a second concept of time to that of the first of the communication device or medical device.
A ninth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the communication device further comprises a CD timing module, a CD crystal oscillator, and at least one CD temperature transducer, and wherein the CD timing module uses at least the CD temperature transducer in combination with known properties of the CD crystal oscillator to modify a rate of tracking of time by the CD timing module.
In a specific variation of the ninth aspect of the invention, he modified time is used in transmitting messages to the medical device. In a further variation, the medical device listens only part of the time for incoming messages from the CD telemetry system or transmits unsolicited messages to the communication device only at selected times, and the communication device estimates the medical device""s inbound listening times or potential outbound transmission times based, at least in part, upon at least one temperature measurement made since a last message was exchanged between the medical device and the communication device in combination with known variations in crystal oscillation frequency with temperature.
A tenth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the medical device further comprises an MD timing module, an MD crystal oscillator, and at least one MD temperature transducer, and wherein the MD timing module uses at least the MD temperature transducer in combination with known properties of the MD crystal oscillator to modify a rate of tracking of time by the MD timing module.
An eleventh aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the MD telemetry system is activated to enable reception or transmission of messages only a portion of the time.
A twelfth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the medical device sends out unsolicited messages to the communication device.
A thirteenth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the medical device sends outbound messages to the communication device and the communication device receives outbound messages from the medical device; wherein the medical device receives inbound messages from the communication device and the communication device sends inbound messages to the medical device; wherein the medical device listens for inbound messages beginning at an inbound listening start time and continuing for an inbound listening period; wherein the communication device listens for outbound messages beginning at an outbound listening start time and continuing for an outbound listening period; wherein the medical device transmits outbound messages beginning at an outbound transmission start time and continues transmission of a selected portion of the outbound messages for an outbound transmission period; wherein the communication device transmits inbound messages beginning at an inbound transmission start time and continues transmission of a selected portion of the inbound messages for an inbound transmission period; wherein an interval exists between successive inbound listening periods; wherein an interval exists between successive outbound listening periods; and wherein at least a selected one of (1) or (2) occurs: (1) at least one of the inbound transmission period or the outbound transmission period is extended after a failure to communicate occurs; or (2) at least one of the inbound transmission start times or outbound transmission start times undergoes a shift relative to an anticipated inbound listening start time or an anticipated outbound listening start time, respectively; and wherein after one or more extensions and/or one or more shifts, all portions of the interval between successive inbound or outbound listening periods would be broadcast to during inbound transmission periods or outbound transmission periods, respectively.
A fourteenth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein at least one of the MD telemetry system or the CD telemetry system is configured to establish frame synchronization and to confirm that a message is intended specifically for the medical device or the communication device, respectively, by confirming receipt of a predefined identifier.
A fifteenth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein a timing associated with a transmission of a message or reception of a message, by one of the medical device or the communication device is based, at least in part, on an estimate of the amount of drift in time that has occurred between a present time and a time of a previous synchronization of a timer in the medical device and a timer in the communication device.
A sixteenth aspect of the invention provides a medical system that includes (a) an ambulatory medical device (MD) that includes MD electronic control circuitry that further includes at least one MD telemetry system and at least one MD processor that controls, at least in part, operation of the MD telemetry system and operation of the medical device, wherein the medical device is configured to provide a treatment to a body of a patient or to monitor a selected state of the body; and (b) a communication device (CD) that includes CD electronic control circuitry that further includes at least one CD telemetry system and at least one CD processor that controls, at least in part, operation of the CD telemetry system and operation of the communication device, wherein the CD telemetry system sends messages to or receives messages from the MD telemetry system, wherein the MD telemetry system does not send out a message as the message is generated but instead delays the sending out of a message until a next prescribed outbound transmission start time occurs.
Additional specific variations, provide the medical devices of each of the above aspects and above noted variations as implantable devices such as implantable infusion pumps, implantable physiological sensors, implantable stimulators, and the like, or external devices such subcutaneous delivery infusion pumps or sensors that ascertain a physiological parameter or parameters from subcutaneous tissue or from the skin of the patient. Such infusion pumps may dispense insulin, analgesics, neurological drugs, drugs for treating AIDS, drugs for treating chronic ailments or acute ailments. Sensors may be used to detect various physiological parameters such as hormone levels, insulin, pH, oxygen, other blood chemical constituent levels, and the like. The sensor may be of the electrochemical type, optical type, and may or may not be enzymatic in operation.
In even further variations of the above noted aspects, and above noted variations, one or more of the following is provided: (1) a first portion of the MD telemetry system is incorporated into the MD processor and a second portion of the MD telemetry system is external to the MD processor, (2) a first portion of the CD telemetry system is incorporated into the CD processor and a second portion of the CD telemetry system is external to the CD processor, (3) the MD processor includes an MD central processing unit and at least one other MD functional module, (4) the CD processor includes a CD central processing unit and at least one other CD functional module, (5) the MD electronic control circuitry includes at least one external MD functional module, other than a portion of the MD telemetry system, that is external to the MD processor, or (6) the CD electronic control circuitry includes at least one external CD functional module, other than a portion of the CD telemetry system, that is external to the CD processor.
Still additional aspects of the invention provide method counterparts to the above system aspects as well as to other functional associations and relationships, and processes that have not been specifically set forth above but will be understood by those of skill in the art from a review of the teachings provided herein.
Further aspects of the invention will be understood by those of skill in the art upon reviewing the teachings herein. These other aspects of the invention may provide various combinations of the aspects presented above as well as provide other configurations, structures, functional relationships, and processes that have not been specifically set forth above.